ntp-keygen(8) - phpMan

NTP_KEYGEN(8) BSD System Manager's Manual NTP_KEYGEN(8)

NAME
ntp-keygen -- Create a NTP host key

SYNOPSIS
ntp-keygen [-flags] [-flag [value]] [--option-name[[=| ]value]]

All arguments must be options.

DESCRIPTION
This program generates cryptographic data files used by the NTPv4 authentication and identi-
fication schemes. It can generate message digest keys used in symmetric key cryptography
and, if the OpenSSL software library has been installed, it can generate host keys, signing
keys, certificates, and identity keys and parameters used in Autokey public key cryptogra-
phy. These files are used for cookie encryption, digital signature, and challenge/response
identification algorithms compatible with the Internet standard security infrastructure.

The message digest symmetric keys file is generated in a format compatible with NTPv3. All
other files are in PEM-encoded printable ASCII format, so they can be embedded as MIME at-
tachments in email to other sites and certificate authorities. By default, files are not
encrypted.

When used to generate message digest symmetric keys, the program produces a file containing
ten pseudo-random printable ASCII strings suitable for the MD5 message digest algorithm in-
cluded in the distribution. If the OpenSSL library is installed, it produces an additional
ten hex-encoded random bit strings suitable for SHA1, AES-128-CMAC, and other message digest
algorithms. The message digest symmetric keys file must be distributed and stored using se-
cure means beyond the scope of NTP itself. Besides the keys used for ordinary NTP associa-
tions, additional keys can be defined as passwords for the ntpq(1) and ntpdc(1) utility pro-
grams.

The remaining generated files are compatible with other OpenSSL applications and other Pub-
lic Key Infrastructure (PKI) resources. Certificates generated by this program are compati-
ble with extant industry practice, although some users might find the interpretation of
X509v3 extension fields somewhat liberal. However, the identity keys are probably not com-
patible with anything other than Autokey.

Some files used by this program are encrypted using a private password. The -p option spec-
ifies the read password for local encrypted files and the -q option the write password for
encrypted files sent to remote sites. If no password is specified, the host name returned
by the Unix hostname(1) command, normally the DNS name of the host, is used as the the de-
fault read password, for convenience. The ntp-keygen program prompts for the password if it
reads an encrypted file and the password is missing or incorrect. If an encrypted file is
read successfully and no write password is specified, the read password is used as the write
password by default.

The pw option of the crypto ntpd(8) configuration command specifies the read password for
previously encrypted local files. This must match the local read password used by this pro-
gram. If not specified, the host name is used. Thus, if files are generated by this pro-
gram without an explicit password, they can be read back by ntpd(8) without specifying an
explicit password but only on the same host. If the write password used for encryption is
specified as the host name, these files can be read by that host with no explicit password.

Normally, encrypted files for each host are generated by that host and used only by that
host, although exceptions exist as noted later on this page. The symmetric keys file, nor-
mally called ntp.keys, is usually installed in /etc. Other files and links are usually in-
stalled in /usr/local/etc, which is normally in a shared filesystem in NFS-mounted networks
and cannot be changed by shared clients. In these cases, NFS clients can specify the files
in another directory such as /etc using the keysdir ntpd(8) configuration file command.

This program directs commentary and error messages to the standard error stream stderr and
remote files to the standard output stream stdout where they can be piped to other applica-
tions or redirected to files. The names used for generated files and links all begin with
the string ntpkey* and include the file type, generating host and filestamp, as described in
the Cryptographic Data Files section below.

Running the Program
The safest way to run the ntp-keygen program is logged in directly as root. The recommended
procedure is change to the keys directory, usually /usr/local/etc, then run the program.

To test and gain experience with Autokey concepts, log in as root and change to the keys di-
rectory, usually /usr/local/etc. When run for the first time, or if all files with names
beginning with ntpkey* have been removed, use the ntp-keygen command without arguments to
generate a default RSA host key and matching RSA-MD5 certificate file with expiration date
one year hence, which is all that is necessary in many cases. The program also generates
soft links from the generic names to the respective files. If run again without options,
the program uses the existing keys and parameters and generates a new certificate file with
new expiration date one year hence, and soft link.

The host key is used to encrypt the cookie when required and so must be RSA type. By de-
fault, the host key is also the sign key used to encrypt signatures. When necessary, a dif-
ferent sign key can be specified and this can be either RSA or DSA type. By default, the
message digest type is MD5, but any combination of sign key type and message digest type
supported by the OpenSSL library can be specified, including those using the AES128CMAC,
MD2, MD5, MDC2, SHA, SHA1 and RIPE160 message digest algorithms. However, the scheme speci-
fied in the certificate must be compatible with the sign key. Certificates using any digest
algorithm are compatible with RSA sign keys; however, only SHA and SHA1 certificates are
compatible with DSA sign keys.

Private/public key files and certificates are compatible with other OpenSSL applications and
very likely other libraries as well. Certificates or certificate requests derived from them
should be compatible with extant industry practice, although some users might find the in-
terpretation of X509v3 extension fields somewhat liberal. However, the identification pa-
rameter files, although encoded as the other files, are probably not compatible with any-
thing other than Autokey.

Running the program as other than root and using the Unix su(1) command to assume root may
not work properly, since by default the OpenSSL library looks for the random seed file .rnd
in the user home directory. However, there should be only one .rnd, most conveniently in
the root directory, so it is convenient to define the RANDFILE environment variable used by
the OpenSSL library as the path to .rnd.

Installing the keys as root might not work in NFS-mounted shared file systems, as NFS
clients may not be able to write to the shared keys directory, even as root. In this case,
NFS clients can specify the files in another directory such as /etc using the keysdir
ntpd(8) configuration file command. There is no need for one client to read the keys and
certificates of other clients or servers, as these data are obtained automatically by the
Autokey protocol.

Ordinarily, cryptographic files are generated by the host that uses them, but it is possible
for a trusted agent (TA) to generate these files for other hosts; however, in such cases
files should always be encrypted. The subject name and trusted name default to the hostname
of the host generating the files, but can be changed by command line options. It is conve-
nient to designate the owner name and trusted name as the subject and issuer fields, respec-
tively, of the certificate. The owner name is also used for the host and sign key files,
while the trusted name is used for the identity files.

All files are installed by default in the keys directory /usr/local/etc, which is normally
in a shared filesystem in NFS-mounted networks. The actual location of the keys directory
and each file can be overridden by configuration commands, but this is not recommended.
Normally, the files for each host are generated by that host and used only by that host, al-
though exceptions exist as noted later on this page.

Normally, files containing private values, including the host key, sign key and identifica-
tion parameters, are permitted root read/write-only; while others containing public values
are permitted world readable. Alternatively, files containing private values can be en-
crypted and these files permitted world readable, which simplifies maintenance in shared
file systems. Since uniqueness is insured by the hostname and filestamp file name exten-
sions, the files for an NTP server and dependent clients can all be installed in the same
shared directory.

The recommended practice is to keep the file name extensions when installing a file and to
install a soft link from the generic names specified elsewhere on this page to the generated
files. This allows new file generations to be activated simply by changing the link. If a
link is present, ntpd(8) follows it to the file name to extract the filestamp. If a link is
not present, ntpd(8) extracts the filestamp from the file itself. This allows clients to
verify that the file and generation times are always current. The ntp-keygen program uses
the same filestamp extension for all files generated at one time, so each generation is dis-
tinct and can be readily recognized in monitoring data.

Run the command on as many hosts as necessary. Designate one of them as the trusted host
(TH) using ntp-keygen with the -T option and configure it to synchronize from reliable In-
ternet servers. Then configure the other hosts to synchronize to the TH directly or indi-
rectly. A certificate trail is created when Autokey asks the immediately ascendant host to-
wards the TH to sign its certificate, which is then provided to the immediately descendant
host on request. All group hosts should have acyclic certificate trails ending on the TH.

The host key is used to encrypt the cookie when required and so must be RSA type. By de-
fault, the host key is also the sign key used to encrypt signatures. A different sign key
can be assigned using the -S option and this can be either RSA or DSA type. By default, the
signature message digest type is MD5, but any combination of sign key type and message di-
gest type supported by the OpenSSL library can be specified using the -c option.

The rules say cryptographic media should be generated with proventic filestamps, which means
the host should already be synchronized before this program is run. This of course creates
a chicken-and-egg problem when the host is started for the first time. Accordingly, the
host time should be set by some other means, such as eyeball-and-wristwatch, at least so
that the certificate lifetime is within the current year. After that and when the host is
synchronized to a proventic source, the certificate should be re-generated.

Additional information on trusted groups and identity schemes is on the "Autokey Public-Key
Authentication" page.

File names begin with the prefix ntpkey_ and end with the suffix _hostname. filestamp, where
hostname is the owner name, usually the string returned by the Unix hostname(1) command, and
filestamp is the NTP seconds when the file was generated, in decimal digits. This both
guarantees uniqueness and simplifies maintenance procedures, since all files can be quickly
removed by a rm ntpkey* command or all files generated at a specific time can be removed by
a rm *filestamp command. To further reduce the risk of misconfiguration, the first two
lines of a file contain the file name and generation date and time as comments.

Trusted Hosts and Groups
Each cryptographic configuration involves selection of a signature scheme and identification
scheme, called a cryptotype, as explained in the Authentication Options section of
ntp.conf(5). The default cryptotype uses RSA encryption, MD5 message digest and TC identi-
fication. First, configure a NTP subnet including one or more low-stratum trusted hosts
from which all other hosts derive synchronization directly or indirectly. Trusted hosts
have trusted certificates; all other hosts have nontrusted certificates. These hosts will
automatically and dynamically build authoritative certificate trails to one or more trusted
hosts. A trusted group is the set of all hosts that have, directly or indirectly, a cer-
tificate trail ending at a trusted host. The trail is defined by static configuration file
entries or dynamic means described on the Automatic NTP Configuration Options section of
ntp.conf(5).

On each trusted host as root, change to the keys directory. To insure a fresh fileset, re-
move all ntpkey files. Then run ntp-keygen -T to generate keys and a trusted certificate.
On all other hosts do the same, but leave off the -T flag to generate keys and nontrusted
certificates. When complete, start the NTP daemons beginning at the lowest stratum and
working up the tree. It may take some time for Autokey to instantiate the certificate
trails throughout the subnet, but setting up the environment is completely automatic.

If it is necessary to use a different sign key or different digest/signature scheme than the
default, run ntp-keygen with the -S type option, where type is either RSA or DSA. The most
frequent need to do this is when a DSA-signed certificate is used. If it is necessary to
use a different certificate scheme than the default, run ntp-keygen with the -c scheme op-
tion and selected scheme as needed. If ntp-keygen is run again without these options, it
generates a new certificate using the same scheme and sign key, and soft link.

After setting up the environment it is advisable to update certificates from time to time,
if only to extend the validity interval. Simply run ntp-keygen with the same flags as be-
fore to generate new certificates using existing keys, and soft links. However, if the host
or sign key is changed, ntpd(8) should be restarted. When ntpd(8) is restarted, it loads
any new files and restarts the protocol. Other dependent hosts will continue as usual until
signatures are refreshed, at which time the protocol is restarted.

Identity Schemes
As mentioned on the Autonomous Authentication page, the default TC identity scheme is vul-
nerable to a middleman attack. However, there are more secure identity schemes available,
including PC, IFF, GQ and MV schemes described below. These schemes are based on a TA, one
or more trusted hosts and some number of nontrusted hosts. Trusted hosts prove identity us-
ing values provided by the TA, while the remaining hosts prove identity using values pro-
vided by a trusted host and certificate trails that end on that host. The name of a trusted
host is also the name of its sugroup and also the subject and issuer name on its trusted
certificate. The TA is not necessarily a trusted host in this sense, but often is.

In some schemes there are separate keys for servers and clients. A server can also be a
client of another server, but a client can never be a server for another client. In gen-
eral, trusted hosts and nontrusted hosts that operate as both server and client have parame-
ter files that contain both server and client keys. Hosts that operate only as clients have
key files that contain only client keys.

The PC scheme supports only one trusted host in the group. On trusted host alice run
ntp-keygen -P -p password to generate the host key file ntpkey_ RSA key_alice. filestamp and
trusted private certificate file ntpkey_ RSA-MD5 _ cert_alice. filestamp, and soft links.
Copy both files to all group hosts; they replace the files which would be generated in other
schemes. On each host bob install a soft link from the generic name ntpkey_host_bob to the
host key file and soft link ntpkey_cert_bob to the private certificate file. Note the
generic links are on bob, but point to files generated by trusted host alice. In this
scheme it is not possible to refresh either the keys or certificates without copying them to
all other hosts in the group, and recreating the soft links.

For the IFF scheme proceed as in the TC scheme to generate keys and certificates for all
group hosts, then for every trusted host in the group, generate the IFF parameter file. On
trusted host alice run ntp-keygen -T -I -p password to produce her parameter file
ntpkey_IFFpar_alice.filestamp, which includes both server and client keys. Copy this file
to all group hosts that operate as both servers and clients and install a soft link from the
generic ntpkey_iff_alice to this file. If there are no hosts restricted to operate only as
clients, there is nothing further to do. As the IFF scheme is independent of keys and cer-
tificates, these files can be refreshed as needed.

If a rogue client has the parameter file, it could masquerade as a legitimate server and
present a middleman threat. To eliminate this threat, the client keys can be extracted from
the parameter file and distributed to all restricted clients. After generating the parame-
ter file, on alice run ntp-keygen -e and pipe the output to a file or email program. Copy
or email this file to all restricted clients. On these clients install a soft link from the
generic ntpkey_iff_alice to this file. To further protect the integrity of the keys, each
file can be encrypted with a secret password.

For the GQ scheme proceed as in the TC scheme to generate keys and certificates for all
group hosts, then for every trusted host in the group, generate the IFF parameter file. On
trusted host alice run ntp-keygen -T -G -p password to produce her parameter file
ntpkey_GQpar_alice.filestamp, which includes both server and client keys. Copy this file to
all group hosts and install a soft link from the generic ntpkey_gq_alice to this file. In
addition, on each host bob install a soft link from generic ntpkey_gq_bob to this file. As
the GQ scheme updates the GQ parameters file and certificate at the same time, keys and cer-
tificates can be regenerated as needed.

For the MV scheme, proceed as in the TC scheme to generate keys and certificates for all
group hosts. For illustration assume trish is the TA, alice one of several trusted hosts
and bob one of her clients. On TA trish run ntp-keygen -V n -p password, where n is the
number of revokable keys (typically 5) to produce the parameter file
ntpkeys_MVpar_trish.filestamp and client key files ntpkeys_MVkeyd _ trish. filestamp where d
is the key number (0 < d < n). Copy the parameter file to alice and install a soft link
from the generic ntpkey_mv_alice to this file. Copy one of the client key files to alice
for later distribution to her clients. It does not matter which client key file goes to al-
ice, since they all work the same way. Alice copies the client key file to all of her
clients. On client bob install a soft link from generic ntpkey_mvkey_bob to the client key
file. As the MV scheme is independent of keys and certificates, these files can be re-
freshed as needed.

Command Line Options
-b --imbits= modulus
Set the number of bits in the identity modulus for generating identity keys to
modulus bits. The number of bits in the identity modulus defaults to 256, but can
be set to values from 256 to 2048 (32 to 256 octets). Use the larger moduli with
caution, as this can consume considerable computing resources and increases the size
of authenticated packets.

-c --certificate= scheme
Select certificate signature encryption/message digest scheme. The scheme can be
one of the following: RSA-MD2, RSA-MD5, RSA-MDC2, RSA-SHA, RSA-SHA1, RSA-RIPEMD160,
DSA-SHA, or DSA-SHA1. Note that RSA schemes must be used with an RSA sign key and
DSA schemes must be used with a DSA sign key. The default without this option is
RSA-MD5. If compatibility with FIPS 140-2 is required, either the DSA-SHA or
DSA-SHA1 scheme must be used.

-C --cipher= cipher
Select the OpenSSL cipher to encrypt the files containing private keys. The default
without this option is three-key triple DES in CBC mode, des-ede3-cbc. The openssl
-h command provided with OpenSSL displays available ciphers.

-d --debug-level
Increase debugging verbosity level. This option displays the cryptographic data
produced in eye-friendly billboards.

-D --set-debug-level= level
Set the debugging verbosity to level. This option displays the cryptographic data
produced in eye-friendly billboards.

-e --id-key
Write the IFF or GQ public parameters from the IFFkey or GQkey client keys file pre-
viously specified as unencrypted data to the standard output stream stdout. This is
intended for automatic key distribution by email.

-G --gq-params
Generate a new encrypted GQ parameters and key file for the Guillou-Quisquater (GQ)
identity scheme. This option is mutually exclusive with the -I and -V options.

-H --host-key
Generate a new encrypted RSA public/private host key file.

-I --iffkey
Generate a new encrypted IFF key file for the Schnorr (IFF) identity scheme. This
option is mutually exclusive with the -G and Fl V options.

-i --ident= group
Set the optional Autokey group name to group. This is used in the identity scheme
parameter file names of IFF, GQ, and MV client parameters files. In that role, the
default is the host name if no group is provided. The group name, if specified us-
ing -i or -s following an '@' character, is also used in certificate subject and is-
suer names in the form host @ group and should match the group specified via crypto
ident or server ident in the ntpd configuration file.

-l --lifetime= days
Set the lifetime for certificate expiration to days. The default lifetime is one
year (365 days).

-m --modulus= bits
Set the number of bits in the prime modulus for generating files to bits. The modu-
lus defaults to 512, but can be set from 256 to 2048 (32 to 256 octets). Use the
larger moduli with caution, as this can consume considerable computing resources and
increases the size of authenticated packets.

-M --md5key
Generate a new symmetric keys file containing 10 MD5 keys, and if OpenSSL is avail-
able, 10 SHA keys. An MD5 key is a string of 20 random printable ASCII characters,
while a SHA key is a string of 40 random hex digits. The file can be edited using a
text editor to change the key type or key content. This option is mutually exclu-
sive with all other options.

-p --password= passwd
Set the password for reading and writing encrypted files to passwd. These include
the host, sign and identify key files. By default, the password is the string re-
turned by the Unix hostname command.

-P --pvt-cert
Generate a new private certificate used by the PC identity scheme. By default, the
program generates public certificates. Note: the PC identity scheme is not recom-
mended for new installations.

-q --export-passwd= passwd
Set the password for writing encrypted IFF, GQ and MV identity files redirected to
stdout to passwd. In effect, these files are decrypted with the -p password, then
encrypted with the -q password. By default, the password is the string returned by
the Unix hostname command.

-s --subject-key= file ... [host] [@ group]
Specify the Autokey host name, where host is the optional host name and group is the
optional group name. The host name, and if provided, group name are used in host @
group form as certificate subject and issuer. Specifying -s -@ group is allowed,
and results in leaving the host name unchanged, as with -i group. The group name,
or if no group is provided, the host name are also used in the file names of IFF,
GQ, and MV identity scheme client parameter files. If host is not specified, the
default host name is the string returned by the Unix hostname command.

-S --sign-key= [RSA | DSA]
Generate a new encrypted public/private sign key file of the specified type. By de-
fault, the sign key is the host key and has the same type. If compatibility with
FIPS 140-2 is required, the sign key type must be DSA.

-T --trusted-cert
Generate a trusted certificate. By default, the program generates a non-trusted
certificate.

-V --mv-params nkeys
Generate nkeys encrypted server keys and parameters for the Mu-Varadharajan (MV)
identity scheme. This option is mutually exclusive with the -I and -G options.
Note: support for this option should be considered a work in progress.

Random Seed File
All cryptographically sound key generation schemes must have means to randomize the entropy
seed used to initialize the internal pseudo-random number generator used by the library rou-
tines. The OpenSSL library uses a designated random seed file for this purpose. The file
must be available when starting the NTP daemon and ntp-keygen program. If a site supports
OpenSSL or its companion OpenSSH, it is very likely that means to do this are already avail-
able.

It is important to understand that entropy must be evolved for each generation, for other-
wise the random number sequence would be predictable. Various means dependent on external
events, such as keystroke intervals, can be used to do this and some systems have built-in
entropy sources. Suitable means are described in the OpenSSL software documentation, but
are outside the scope of this page.

The entropy seed used by the OpenSSL library is contained in a file, usually called .rnd,
which must be available when starting the NTP daemon or the ntp-keygen program. The NTP
daemon will first look for the file using the path specified by the randfile subcommand of
the crypto configuration command. If not specified in this way, or when starting the
ntp-keygen program, the OpenSSL library will look for the file using the path specified by
the RANDFILE environment variable in the user home directory, whether root or some other
user. If the RANDFILE environment variable is not present, the library will look for the
.rnd file in the user home directory. Since both the ntp-keygen program and ntpd(8) daemon
must run as root, the logical place to put this file is in /.rnd or /root/.rnd. If the file
is not available or cannot be written, the daemon exits with a message to the system log and
the program exits with a suitable error message.

Cryptographic Data Files
All file formats begin with two nonencrypted lines. The first line contains the file name,
including the generated host name and filestamp, in the format ntpkey_key _ name. filestamp,
where key is the key or parameter type, name is the host or group name and filestamp is the
filestamp (NTP seconds) when the file was created. By convention, key names in generated
file names include both upper and lower case characters, while key names in generated link
names include only lower case characters. The filestamp is not used in generated link
names. The second line contains the datestamp in conventional Unix date format. Lines be-
ginning with '#' are considered comments and ignored by the ntp-keygen program and ntpd(8)
daemon.

The remainder of the file contains cryptographic data, encoded first using ASN.1 rules, then
encrypted if necessary, and finally written in PEM-encoded printable ASCII text, preceded
and followed by MIME content identifier lines.

The format of the symmetric keys file, ordinarily named ntp.keys, is somewhat different than
the other files in the interest of backward compatibility. Ordinarily, the file is gener-
ated by this program, but it can be constructed and edited using an ordinary text editor.

# ntpkey_MD5key_bk.ntp.org.3595864945
# Thu Dec 12 19:22:25 2013
1 MD5 L";Nw<`.I<f4U0)247"i # MD5 key
2 MD5 &>l0%XXK9O'51VwV<xq~ # MD5 key
3 MD5 lb4zLW~d^!K:]RsD'qb6 # MD5 key
4 MD5 Yue:tL[+vR)M`n~bY,'? # MD5 key
5 MD5 B;fx'Kgr/&4ZTbL6=RxA # MD5 key
6 MD5 4eYwa`o}3i@@V@..R9!l # MD5 key
7 MD5 `A.([h+;wTQ|xfi%Sn_! # MD5 key
8 MD5 45:V,r4]l6y^JH6"Sh?F # MD5 key
9 MD5 3-5vcn*6l29DS?Xdsg)* # MD5 key
10 MD5 2late4Me # MD5 key
11 SHA1 a27872d3030a9025b8446c751b4551a7629af65c # SHA1 key
12 SHA1 21bc3b4865dbb9e920902abdccb3e04ff97a5e74 # SHA1 key
13 SHA1 2b7736fe24fef5ba85ae11594132ab5d6f6daba9 # SHA1 key
14 SHA a5332809c8878dd3a5b918819108a111509aeceb # SHA key
15 MD2 2fe16c88c760ff2f16d4267e36c1aa6c926e6964 # MD2 key
16 MD4 b2691811dc19cfc0e2f9bcacd74213f29812183d # MD4 key
17 MD5 e4d6735b8bdad58ec5ffcb087300a17f7fef1f7c # MD5 key
18 MDC2 a8d5e2315c025bf3a79174c87fbd10477de2eabc # MDC2 key
19 RIPEMD160 77ca332cafb30e3cafb174dcd5b80ded7ba9b3d2 # RIPEMD160 key
20 AES128CMAC f92ff73eee86c1e7dc638d6489a04e4e555af878 # AES128CMAC key
Figure 1. Typical Symmetric Key File

Figure 1 shows a typical symmetric keys file used by the reference implementation. Follow-
ing the header the keys are entered one per line in the format
keyno type key
where keyno is a positive integer in the range 1-65535; type is the key type for the message
digest algorithm, which in the absence of the OpenSSL library must be MD5 to designate the
MD5 message digest algorithm; if the OpenSSL library is installed, the key type can be any
message digest algorithm supported by that library; however, if compatibility with FIPS
140-2 is required, the key type must be either SHA or SHA1; key is the key itself, which is
a printable ASCII string 20 characters or less in length: each character is chosen from the
93 printable characters in the range 0x21 through 0x7e ( ''! through '~' ) excluding space
and the '#' character, and terminated by whitespace or a '#' character. An OpenSSL key con-
sists of a hex-encoded ASCII string of 40 characters, which is truncated as necessary.

Note that the keys used by the ntpq(1) and ntpdc(1) programs are checked against passwords
requested by the programs and entered by hand, so it is generally appropriate to specify
these keys in human readable ASCII format.

The ntp-keygen program generates a symmetric keys file ntpkey_MD5key_hostname.filestamp.
Since the file contains private shared keys, it should be visible only to root and distrib-
uted by secure means to other subnet hosts. The NTP daemon loads the file ntp.keys, so
ntp-keygen installs a soft link from this name to the generated file. Subsequently, similar
soft links must be installed by manual or automated means on the other subnet hosts. While
this file is not used with the Autokey Version 2 protocol, it is needed to authenticate some
remote configuration commands used by the ntpq(1) and ntpdc(1) utilities.

OPTIONS
-b imbits, --imbits=imbits
identity modulus bits. This option takes an integer number as its argument. The
value of imbits is constrained to being:
in the range 256 through 2048

The number of bits in the identity modulus. The default is 256.

-c scheme, --certificate=scheme
certificate scheme.

scheme is one of RSA-MD2, RSA-MD5, RSA-MDC2, RSA-SHA, RSA-SHA1, RSA-RIPEMD160,
DSA-SHA, or DSA-SHA1.

Select the certificate signature encryption/message digest scheme. Note that RSA
schemes must be used with a RSA sign key and DSA schemes must be used with a DSA
sign key. The default without this option is RSA-MD5.

-C cipher, --cipher=cipher
privatekey cipher.

Select the cipher which is used to encrypt the files containing private keys. The
default is three-key triple DES in CBC mode, equivalent to "-C des-ede3-cbc". The
openssl tool lists ciphers available in "openssl -h" output.

-d, --debug-level
Increase debug verbosity level. This option may appear an unlimited number of
times.

-D number, --set-debug-level=number
Set the debug verbosity level. This option may appear an unlimited number of times.
This option takes an integer number as its argument.

-e, --id-key
Write IFF or GQ identity keys.

Write the public parameters from the IFF or GQ client keys to the standard output.
This is intended for automatic key distribution by email.

-G, --gq-params
Generate GQ parameters and keys.

Generate parameters and keys for the GQ identification scheme, obsoleting any that
may exist.

-H, --host-key
generate RSA host key.

Generate new host keys, obsoleting any that may exist.

-I, --iffkey
generate IFF parameters.

Generate parameters for the IFF identification scheme, obsoleting any that may ex-
ist.

-i group, --ident=group
set Autokey group name.

Set the optional Autokey group name to name. This is used in the file name of IFF,
GQ, and MV client parameters files. In that role, the default is the host name if
this option is not provided. The group name, if specified using -i/--ident or using
-s/--subject-name following an '@' character, is also a part of the self-signed host
certificate subject and issuer names in the form host@group and should match the
'crypto ident' or 'server ident' configuration in the ntpd configuration file.

-l lifetime, --lifetime=lifetime
set certificate lifetime. This option takes an integer number as its argument.

Set the certificate expiration to lifetime days from now.

-m modulus, --modulus=modulus
prime modulus. This option takes an integer number as its argument. The value of
modulus is constrained to being:
in the range 256 through 2048

The number of bits in the prime modulus. The default is 512.

-M, --md5key
generate symmetric keys.

Generate symmetric keys, obsoleting any that may exist.

-P, --pvt-cert
generate PC private certificate.

Generate a private certificate. By default, the program generates public certifi-
cates.

-p passwd, --password=passwd
local private password.

Local files containing private data are encrypted with the DES-CBC algorithm and the
specified password. The same password must be specified to the local ntpd via the
"crypto pw password" configuration command. The default password is the local host-
name.

-q passwd, --export-passwd=passwd
export IFF or GQ group keys with password.

Export IFF or GQ identity group keys to the standard output, encrypted with the
DES-CBC algorithm and the specified password. The same password must be specified
to the remote ntpd via the "crypto pw password" configuration command. See also the
option --id-key (-e) for unencrypted exports.

-s host@group, --subject-name=host@group
set host and optionally group name.

Set the Autokey host name, and optionally, group name specified following an '@'
character. The host name is used in the file name of generated host and signing
certificates, without the group name. The host name, and if provided, group name
are used in host@group form for the host certificate subject and issuer fields.
Specifying '-s @group' is allowed, and results in leaving the host name unchanged
while appending @group to the subject and issuer fields, as with -i group. The
group name, or if not provided, the host name are also used in the file names of
IFF, GQ, and MV client parameter files.

-S sign, --sign-key=sign
generate sign key (RSA or DSA).

Generate a new sign key of the designated type, obsoleting any that may exist. By
default, the program uses the host key as the sign key.

-T, --trusted-cert
trusted certificate (TC scheme).

Generate a trusted certificate. By default, the program generates a non-trusted
certificate.

-V num, --mv-params=num
generate <num> MV parameters. This option takes an integer number as its argument.

Generate parameters and keys for the Mu-Varadharajan (MV) identification scheme.

-v num, --mv-keys=num
update <num> MV keys. This option takes an integer number as its argument.

This option has not been fully documented.

-?, --help
Display usage information and exit.

-!, --more-help
Pass the extended usage information through a pager.

-> [cfgfile], --save-opts [=cfgfile]
Save the option state to cfgfile. The default is the last configuration file listed
in the OPTION PRESETS section, below. The command will exit after updating the con-
fig file.

-< cfgfile, --load-opts=cfgfile, --no-load-opts
Load options from cfgfile. The no-load-opts form will disable the loading of ear-
lier config/rc/ini files. --no-load-opts is handled early, out of order.

--version [{v|c|n}]
Output version of program and exit. The default mode is `v', a simple version. The
`c' mode will print copyright information and `n' will print the full copyright no-
tice.

OPTION PRESETS
Any option that is not marked as not presettable may be preset by loading values from con-
figuration ("RC" or ".INI") file(s) and values from environment variables named:
NTP_KEYGEN_<option-name> or NTP_KEYGEN
The environmental presets take precedence (are processed later than) the configuration
files. The homerc files are "$HOME", and ".". If any of these are directories, then the
file .ntprc is searched for within those directories.

USAGE
ENVIRONMENT
See OPTION PRESETS for configuration environment variables.

FILES
See OPTION PRESETS for configuration files.

EXIT STATUS
One of the following exit values will be returned:

0 (EXIT_SUCCESS)
Successful program execution.

1 (EXIT_FAILURE)
The operation failed or the command syntax was not valid.

66 (EX_NOINPUT)
A specified configuration file could not be loaded.

70 (EX_SOFTWARE)
libopts had an internal operational error. Please report it to auto-
gen-users AT lists.net. Thank you.

AUTHORS
The University of Delaware and Network Time Foundation

BUGS
It can take quite a while to generate some cryptographic values.

Please report bugs to http://bugs.ntp.org .

Please send bug reports to: http://bugs.ntp.org, bugs AT ntp.org

NOTES
Portions of this document came from FreeBSD.

This manual page was AutoGen-erated from the ntp-keygen option definitions.

BSD June 23 2020 BSD

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